Cooking oil filtering method using automatic sequence controller for plural vats

ABSTRACT

A cooking oil filtering method comprises the steps of connecting the drain outlets of a series of cooking vats to a pre-filter via inlet valves controlling the connection of each vat to the pre-filter, connecting the outlet of the pre-filter to a second filter assembly, connecting the outlet of the second filter assembly to the inlets of the cooking vats via return valves controlling the return of oil to each vat, and controlling operation of a pump and opening of the inlet and return valves to successively pump oil from each vat in turn through the pre-filter and filter assembly before returning it to the vat.

This is a division of Ser. No. 135,597, filed Dec. 21, 1987, now U.S.Pat. No. 4,826,590.

BACKGROUND OF THE INVENTION

The present invention relates to a method for re-circulating andfiltering cooking oil or fat from a cooking vat or broiler.

Most restaurants and large kitchens employ one or more large cookingvats containing a suitable heated cooking oil for cooking foods such asfried chicken, french fries and the like. The cooking oil in the vatsbecomes dirty after a time as a result of small food particles whichseparate from the food being cooked. Thus the oil must be cleaned, andmust be replaced periodically with new oil, resulting in expense andlost cooking time. Also, the vat itself must periodically be emptied andcleaned. Some cooking vats are provided with individual re-circulatingfilters for removing large size particles from the oil. However, thesedo not clean all the particles from the oil, and the oil must still bereplaced relatively often.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved systemfor filtering cooking oil.

According to the present invention, a cooking oil filtering system isprovided which comprises a pre-filter for removing large particles fromcooking oil, and a second filter assembly connected to the pre-filteroutlet for removing smaller size particles from the oil. A filter inletmanifold connected to the pre-filter inlet includes a series of inletpassageways for connection to a series of cooking vat drain outlets. Aninlet valve in each of the inlet passageways controls connection of therespective cooking vat to the pre-filter. A filter outlet or returnmanifold is connected to the outlet of the second filter assembly andhas a series of outlet passageways for connection to a series of cookingvat inlets. An outlet or return valve is connected in each of the outletpassageways to control the return of cleaned oil to the respectivecooking vat. A pump is provided in the system for circulating oil fromthe cooking vats through the filters and back into the cooking vats.

A suitable control assembly is provided for controlling opening andclosing of the inlet and outlet valves. This may comprise a suitablyprogrammed timer and sequence controller. The controller may be set upso that the oil in each vat in a series is cleaned in turn, and cleanoil is returned to the vat before the next vat is connected to thefilter system. This allows the cooking vats to remain in operation whilethe oil in any one of the vats is being filtered. A suitable sequence ofoperations would be first to open an inlet valve connecting a first vatto the pre-filter, simultaneously opening the outlet valve in theconnecting passageway between the second filter assembly and the firstvat. At this point, all other inlet and outlet valves will be closed.The pump will then start to circulate oil from the first vat through thefilters and back to the vat. The inlet and outlet valves to the firstvat are then closed while the second vat in the system is connected tothe pre-filter, and so on until the oil in all the cooking vats has beenfiltered.

According to another aspect of the invention a method of filteringcooking oil is provided, comprising the steps of connecting the outletdrains of a series of cooking vats to a pre-filter, connecting thepre-filter outlet to a second filter assembly, and connecting the outletfrom the second filter assembly to the inlets of each of the cookingvats, and pumping oil from each of the cooking vats in turn through thepre-filter and second filter assembly back to the cooking vat.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from the followingdetailed description of a preferred embodiment of the invention, takenin conjunction with the accompanying drawings, in which like referencenumerals refer to like parts, and in which:

FIG. 1 is a schematic illustration of a complete cooking oil filtersystem according to a preferred embodiment of the invention;

FIG. 2 is a side elevation view, with portions cut away, of one filterunit of the system;

FIG. 3 is a lower end view of a spiral wound filter element; and

FIG. 4 is a side elevation view, with the housing cut away, of anenclosed and heated filter assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 of the drawings shows a preferred embodiment of the cooking oilfilter system according to the invention. The system basically comprisesa pre-filter 10 for removing relatively large size particles fromcooking oil, and a second filter assembly 12 for removing smallerparticles from the oil. The second filter assembly in the preferredembodiment shown comprises a series of individual filters 14, describedin more detail below in connection with FIG. 2.

An inlet manifold 15 connected to the pre-filter inlet 16 comprises aconduit connected to a series of inlet passageways 18 for connection tosuitable outlets 20 provided on a series of cooking vats 22. Althoughthree cooking vats are shown in FIG. 1, it is clear that a greater orlesser number of cooking vats could be connected to the system with theprovision of a suitable number of passageways 18. An inlet or intakevalve 24 is provided in each of the inlet passageways.

A passageway or connecting pipe 26 connects the pre-filter outlet 28 viapump 30 to an intake manifold 32 of the second filter assembly. Intakemanifold 32 includes a series of intake passageways 34 each connected tothe inlet 35 of a respective one of the individual filters 14. An outputor return manifold 36 connects the outlets 37 of each of the filters toa series of return passageways 38 for connection to suitable inlets 39provided on each of the cooking vats. A return valve 40 is provided ineach of the return passageways.

All of the connecting manifolds and passageways in the system are builtto handle normal cooking fat temperatures up to 400° F. The arrows inFIG. 1 illustrate the flow of oil through the filter system. A suitabletimer and sequence controller 42, which may comprise a suitablyprogrammed microprocessor, is connected to each of the intake and returnvalves and to a motor 44 for operating the pump 30 to control thecirculation of oil through the system. The controller provides suitableelectrical signals to the valves to control opening and closing of thevalves, which may be solenoid operated valves, for example.

In the preferred embodiment of the invention, pre-filter 10 is a simple,stainless steel wire basket filter for removing larger particles fromthe oil circulating through it. The second filter assembly comprises aseries of identical, smaller gauge filters, one of which is shown inmore detail in FIG. 2 of the drawings.

As shown in FIG. 2, each filter 14 includes a filtering devicecomprising a roll 46 of filter paper spirally wound on a dowel 48. Thedowel has a transverse pin 50 at one end extending across the end of theroll to retain it on the dowel, as indicated in FIG. 3. The filteringdevice sits on base plate 51 having a series of openings 52 to allow oilto pass through the plate 51 and into outlet passageway 37. A wire mesh54 covers the upper surface of plate 50 for additional filtering, andthe entire filter assembly is enclosed in a cylindrical housing 56having an inlet opening 58 at its upper end for connection to one of theintake passageways 34. The housing 56 has a removable cover or lid 60 toallow periodic replacement of the filter roll 46. The dowel 48 has aring 62 at its upper end to allow the filter roll to be lifted out ofthe housing easily when the roll needs replacing. The individual filters14 can thus be relatively inexpensive and small scale, with the numberof filters chosen according to the volume of oil to be handled in thesystem. The filter rolls can be changed quickly and easily with littleinterruption to normal operations. In a preferred embodiment of theinvention filter rolls of about 51/2 inches in diameter and 31/2 to 4inches in length were used. An optimum oil flow rate was found to be 1/2gallon/minute/filter roll. Thus in a system having 4 filter elements, apump having a capacity of about 1.8 gallons per minute may be used foroptimum efficiency.

Oil entering the housing 56 via inlet 35 thus travels downwardly throughroll 46 and mesh 54 into the outlet 37, with the majority of therelatively small scale particles in the oil being trapped in the roll ofpaper 46.

The timer and sequence controller may be programmed to connect each ofthe cooking vats to the system in sequence so that the oil in each vatis cleaned and returned to that vat before connection of the next vat.In this manner all of the vats can remain in use at all times so thatcleaning can be carried out during normal cooking hours, reducingmanpower requirements. Before start-up, all of the inlet and outletvalves will be closed. On initiation of the programmed filteringsequence, the inlet valve 24 connected to the drain of a first cookingvat is opened and the pump motor is turned on to pump oil through thepre-filter 10.

The oil will circulate through the pre-filter and via intake manifold 32through the filters 14 of the second filter assembly, so that themajority of particles are removed from the oil. The oil return valve 40will be open to a)low the cleaned oil to return to the vat. Once the oilhas been sufficiently filtered, as determined by a timer in thecontroller, for example, the inlet and return valves connected to thesecond vat are opened to allow the oil in that vat to be pumped out andthrough the filters, while the inlet and return valves connected to thefirst vat are closed. The sequence is continued until the oil in all thevats has been cleaned. At this point the sequence may be repeated, orthe system may be turned off until another cleaning sequence isnecessary.

The controller may also be provided with a programmed sequence to allowthe filter rolls to be replaced when necessary. In this sequence, allinlet valves will be closed, all return valves will be open and anadditional valve venting the system to the atmosphere will be opened.This allows air to enter and purge oil from the filter. After asufficient time lapse, the pump is turned off so that the filters can bechanged, after which the timer is re-started for normal cleaningoperation.

FIG. 4 of the drawings shows a modification of the system for use withcooking vats using digestible solid cooking fat, such as lard,shortening or the like, which normally melts at around 100° F. In thiscase the fat must be kept liquid as it circulates through the filtersystem. The pre-filter 10 is mounted at the center of a closedcylindrical housing 70, with the filters 14 mounted in a circular arrayaround pre-filter 10, as indicated in FIG. 4. A suitable heater, such asa 100 Watt light bulb 72 as shown in the drawings, is provided in thehousing. The light bulb or heater 72 may be turned on manually or underthe control of controller 42 when the system is on or off as needed tokeep the fat liquid. The intake and output manifolds are suitablymodified for connection to the inlets and outlets of the filters in thecircular array, as indicated in FIG. 4. Pump 30 is preferably alsomounted inside the housing as shown. Housing 70 has a removable cover 74to allow the pre-filter 10 to be cleaned and the filter rolls of filter14 to be replaced. In this modified embodiment the system is otherwiseidentical to that shown in FIGS. 1 to 3 and like reference numerals areused as appropriate to indicate equivalent parts.

With the filtering system of this invention cooking oil is cleanedquickly and efficiently, and can be kept clean enough to use for a muchlonger period before replacement with new oil. For example, with cookingvats connected to a single wire basket filter for cleaning, oil normallyneeds replacing at least twice a week. With the system of thisinvention, the oil needs replacing considerably less frequently, inpractice no more often than once a month. The system can be connected toa number of vats to be cleaned sequentially, and thus is more economicalsince there is no need to purchase and operate a separate system foreach cooking vat. It can be programmed to operate a cleaning sequenceautomatically during normal cooking hours, significantly reducingoperator time during the cleaning process.

Although a preferred embodiment of the invention has been describedabove by way of example only, it will be understood by those skilled inthe field that modifications may be made to the disclosed inventionwithout departing from the scope of the invention, which is defined bythe appended claims.

I claim:
 1. A method of filtering cooking oil from a series of cookingvats, comprised the steps of:connecting the drain outlets of a series ofcooking vats to a pre-filter via inlet valves controlling the connectionof each vat to the pre-filter; connecting a pre-filter outlet to asecond filter assembly; connecting an outlet of the second filterassembly to the inlets of a series of cooking vats via return valves forcontrolling the return of filtered oil to the cooking vats; connecting apump to pump oil from a cooking vat through the pre-filter and secondfilter assembly; connecting the pump and each of the inlet and returnvalves to an automatic sequence controller; and programming the sequencecontroller to carry out an automatic filtering sequence in whichoperation of the pump and opening of the inlet and return valves arecontrolled to successively pump oil automatically from each vat in turnthrough the pre-filter and filter assembly, and return filtered oil tothe vat.
 2. The method as claimed in claim 1, wherein the step ofpumping oil through the filter assembly comprises pumping oil through aseries of identical filter housings connected in parallel and havingremovable filter elements, and further including a procedure forreplacing the filter elements at selected intervals, the filter elementreplacement procedure comprising opening all the return valvessimultaneously and at the same time venting the system to theatmosphere, operating the pump and allowing oil to purge from thefilters for a predetermined interval, turning off the pump and removingeach filter element by lifting it from its filter housing and replacinga new filter element in each housing.
 3. The method as claimed in claim1, wherein the step of pumping oil through the second filter assemblycomprises pumping oil through a series of identical outer filterhousings connected in parallel, the oil being pumped between an inlet atone end of each filter housing and an outlet at the opposite end througha roll of filter paper wound on an imperforate dowel.
 4. A cooking oilfiltering method, comprising the steps of:connecting a series ofcontainers of cooking oil to be filtered to a pre-filter via inletvalves controlling the connection of each container to the pre-filter;connecting each of the containers to an outlet of a second filterassembly via return valves for controlling the return of filtered oil tothe respective containers; connecting the outlet and return valves and apump for pumping oil from the containers through the pre-filter andfilter assembly to an automatic controller for controlling operation ofthe pump and opening and closing of the valves according to apredetermined control sequence; and operating the automatic controllerto successively pump oil from each container in turn through thepre-filter and second filter assembly and to return filtered oil to thecontainer while the inlet and return valves of the other containers areclosed.